Sun Guangfang, Luan Mingda, Xue Shuting, Yan Jun, Lan Wenzhi
Institute of Future Agriculture, Northwest A&F University, Yangling, Shaanxi, China.
Plant Cell Environ. 2025 Jan;48(1):587-598. doi: 10.1111/pce.15166. Epub 2024 Sep 18.
The vacuolar H-ATPase (V-ATPase) plays a crucial role in facilitating nutrient ions storage in vacuoles, whereas its direct impact on vacuolar phosphate (Pi) accumulation has not been fully elucidated. Previous research revealed that the absence of VPT1 and VPT3, two major vacuolar Pi influx transporters, significantly affected vacuolar Pi storage. This study shows that disrupting V-ATPase function could mimic the vpt1 vpt3 mutant phenotypes. The vha-a2 a3 mutant, lacking V-ATPase activity, had lower vacuolar Pi levels, higher cytoplasmic Pi and increased resistance to As(V) toxicity under sufficient Pi conditions. Complementation assays in Pi transport-deficient yeast confirmed that high pH suppressed VPT1 activity, while overexpressing VPT1 couldn't overload Pi in vacuoles of vha-a2 a3 mutants. These data illustrate the reliance of VPT1's activity on V-ATPase-generated proton gradients. Furthermore, we find V-ATPase activity correlates positively with Pi availability, and varying across developmental stages. During flowering, V-ATPase activity decreases to enhance Pi allocation in xylem sap for long-distance transport when external Pi is replete, akin to the vpt1 vpt3 mutant. Thus, V-ATPase could cooperate with VPT proteins to regulate Pi homeostasis at both subcellular and systemic levels.
液泡H⁺-ATP酶（V-ATP酶）在促进养分离子储存在液泡中起着关键作用，而其对液泡磷酸盐（Pi）积累的直接影响尚未完全阐明。先前的研究表明，两种主要的液泡Pi流入转运蛋白VPT1和VPT3的缺失显著影响液泡Pi储存。本研究表明，破坏V-ATP酶功能可模拟vpt1 vpt3突变体表型。缺乏V-ATP酶活性的vha-a2 a3突变体在充足Pi条件下具有较低的液泡Pi水平、较高的细胞质Pi以及对As（V）毒性的抗性增加。在Pi转运缺陷型酵母中的互补试验证实，高pH抑制VPT1活性，而过表达VPT1不能使vha-a2 a3突变体的液泡中Pi过载。这些数据说明了VPT1活性对V-ATP酶产生的质子梯度的依赖性。此外，我们发现V-ATP酶活性与Pi可用性呈正相关，并且在不同发育阶段有所变化。在开花期间，当外部Pi充足时，V-ATP酶活性降低，以增强木质部汁液中Pi的分配用于长距离运输，类似于vpt1 vpt3突变体。因此，V-ATP酶可以与VPT蛋白协同作用，在亚细胞和系统水平上调节Pi稳态。
